1. Field of the Invention
The present invention relates to an image forming apparatus having a function to print a plurality of documents in a sheet of paper.
2. Description of the Prior Art
An electrophotographic copying machine has various modes. For example, automatic color selection mode may be provided to decide a color document or a monochromatic document. If a document to be copied is decided to be a color document, a color copy is printed, while if the document is decided to be a monochromatic document, a monochromatic copy is printed.
On the other hand, there is also known a mode to print a plurality of documents in a sheet of paper. This mode is referred to as N-in-1 mode where N documents are printed in a sheet of paper. For example, N=2 or 4. However, N documents to be copied in a sheet of paper may include both color and monochromatic documents. Then, N-in-1 mode may not be combined with the automatic selection mode.
A user may want a color print if the N documents include at least one color document. On the other hand, another user may want a color print only if all the N documents are color documents, in order to decrease copy costs because color copy is expensive. Then, when N-in-1 mode is used, a user has to select color copy or monochromatic copy for each N documents. Therefore, copy operation takes a longer time and labor in N-in-1 mode.